Block-signal system.



L. A. HAWKINS.

BLOCK SIGNAL SYSTEM.

APPLICATION TILED NOV. 26, 1909.

1,126,459. Patented Ja11.26,1915.

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L. A. HAWKINS.

BLOCK SIGNAL SYSTEM.

APPLIGATION FILED NOV. 26,1909.

Patented Jan. 26, 1915.

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Ms AT TUHMEY INK "ENTER LAURENCE A Hawzzzms I I FTNESEE O. M Z 2% BY UNlTlED TATES PALNT LAURENCE A. HAWKINS, 01: SCI-IENECTADY, NEW YORK, ASSIGNOR, BY lfiEgNE ASSIGN- MENTS, T0 THE UNIUN SWITC AND SIGNAL COMPANY, A CORPORATION OF EENNSYLVANIA.

BLOCK-SIGNAL SYSTEM.

Application fiIed November 26, 1909.

To 6455 whom it may concern Be it known that I, LAURENCE A. HAW- KINS, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Block-Signal Systems, of which the following is a specification.

My invention relates to alternating current block si 'nal systems and its object is to provide a novel arrangement of control circuits whereby the number of line wires is reduced to a minimum and certain other advantages obtained which will be pointed out hereinafter.

My invention is particularly applicable to systems in which the source of alternating current for each track circuit is connected to the rails near the center of the block. In such a system, which is specially adapted for use where the blocks are long, a relay is placed at each end of the track circuit and a line circuit is extended through the block, so that both relays may control the signal for the block. If the signals are to indicate the condition of two successive blocks or, in other words, to indicate danger, caution and clear, my invention makes it possible to obtain this control without adding other line wires and without opening the signal controlling line circuit except when a track relay for that block is deenergized so that the signal should go to danger. I accomplish this result by employing the track relay at the exit end of the block to open the signal controlling circuit to put the signal to danger and arranging the contacts controlled by the signal for the block in advance for shifting the phase of the current in the line circuit, together with means responsive to the shifting of the current phase for controlling the several signal indications.

My invention will be best understood by reference to the accompanying drawings, in which- Figure 1 shows a block signal system arranged in accordance with my invention; Figs. 2 to 5 are explanatory vector diagrams; Fig. 6 shows a modification of the system, and Figs. 7 to 11 are explanatory vector diagrams.

In Fig. 1, A represents a two-phase generator supplying voltage to the line wires a, a and a These line wires constitute athree Patented Jan. eh,

Serial No. 529,861.

wire, two phase, transmission system, the conductor a serving as a common return for both phases. B represents a transformer having its primary connected across one phase of the transmission system and its secondary connected across the rails of the track circuit at a point near its middle through a resistance or impedance Z), which serves to limit the flow of current from the transformer when short-circuited by a train. C to C represent track relays. The relays C and C belong to the track circuit supplied from the transformer B. Each of these relays is shown diagrammatically as of the well-known two phase induction type, comprising a short-circuited secondary member 0 controlling the relay contacts, a winding 0 connected to the track rails, and a second winding 0 supplied with current independently of the track circuits, but cooperating with the track winding to produce the relay torque. D, D represent home signals, and E, E distant signals for the blocks. It will be understood that while I have shown two-arm two-position signals for giving the three indications, that my invention is equally applicable to the wellknown equivalent of one-arm three-position signals. (Z represents a contact controlled by the home signal. F to F represent transformers for supplying current to the signal mechanisms and also to the relay windings not connected to the track circuits. G and G represent line relays which are also indicated as being of the two-phase type.

It will be seen that the home signal D is directly controlled by the track relay C, so that it the track winding of this relay is short-circuited by a train the signal will go to stop position. Also it the relay G is deenergized the signal D will go to stop position, since the opening of the contacts of relay C breaks the circuit of the winding 0 of relay G. In other words, as long as the track circuit supplied by the trans former B is occupied by a train, home signal D is at stop position, while if the block is clear both relays C and C are energized and signal I) is in a clear position as shown. lVith a train as indicated at H in the block guarded by the home signal D, that signal stands at stop position as does also the distant signal E at the entrance to the preced-v ing block. The control of this distant signal is obtained through the same circuit that controls the winding 0 of relay C by means of the contact cl, actuated by signal D and by the line relay G. This control can best be understood by reference to the vector diagrams of Figs. 2 to 5.

In Fig. 3 0 6 represents the phase of the electromotive force of transformer B, and

0 i represents the phase of the current supplied to the track circuit by this transformer. This current is shown as lagging behind the electromotive force by a comparatively small angle, as would be the case if the resistance Z) were non-inductive, the rails themselves offering a comparatively high ohmic resistance to alternating current because of the well-known skin effect.

Figs. 2 and 5 show the conditions in re lays C and C, respectively. The track winding of each of these relays is traversed by the current 0 i supplied to the track circuit by the transformer B. The winding 0 of relay C is shown connected to another phase than that to which the transformer B is connected, so that the voltage impressed on this winding may be represented in Fig. 2 by 0 6 Since the winding 0 is highly inductive the current in this winding lags behind the impressed voltage by a consider able angle and may be represented by 0 2' The angles between the two currents, 0 i and 0 2' in the two relay windings are shown displaced from each other by approximately 135 degrees. The relay, consequently, has a torque which closes the relay contacts. With the signal D at stop position, as shown, the line circuit comprising the contacts of relay C and the winding 0 of relay C is connected to the transformer F which is of the same phase as the transformer 13, so that the voltage impressed on the winding 0 of relay C may be represented by 0 6. This gives a current in the winding which may be represented by 0 i, which lags behind the track current 0 i by an angle of approximately i5 degrees, which gives in this relay the same torque as in relay C since the sine of 45 degrees is the same as the sine 135 degrees. Now referring to relay Cr, it will be seen that the winding 9' is connected to transformer F, which is of the same phase as transformer F Consequently, the voltage impressed on this winding may be represented in Fig. l by 0 c and the current by 0 The winding 9 is connected in parallel with the winding 0 of relay C, so that the voltage and curent in winding 9 are in phase with the voltage and current in winding 0 that is, with 00 and 02". Comparing Figs with Fig. 5 it will be seen that the voltages and currents in the windings g and g of relay G are in phase, so that relay G has no torque and the circuit of distant signal E is open at the contacts of relay G. T his conditi on continues as long as the signal I) remains at stop position. When the train moves out of the block guarded by this signal, so that signal D clears, the contact cl moves from the position shown to the position shown for the contact (Z at signal D. By this movement the connection of the line circuit for the preceding block is shifted from the transformer F to transformer F so that the voltage in the line circuit is shifted in phase 90 degrees.

' It will be noted that the contact (Z is arranged to close the connection to transformer F before it opens the connections to transformer F so that the line circuit is not opened by the movement of this contact. lmpedances f f are included in the connections to these transformers, so as to avoid short-circuiting the transformers on each. other at the instant when both are connected in parallel to the line circuit. When the contact (Z has moved, as above explained, the voltage impressed on the windings 0 of relay C and g of relay G will be repre sented in Figs. 5 and 1-, respectively, by 0 6* and 0 i shown in dotted lines. In relay C the currents in the two windings are now represented by 0 i and 0 i respectively, and these currents are precisely the same as in relay C so that the relay C still has a torque which has not been affected by the shifting of the phase of the current in the line circuit. The currents in the two windings of relay G are now represented by 0 2' and 0 i displaced from each other by approximately 90 degrees, so that this relay now has a torque and closes the circuit of distant signal E to clear that signal.

It will be noted that the contra 1 of the distant signal is obtained without ncreasing the number of line wires and without opening the line circuit. The line circuit is never opened except when the track relays are deenergized, so that both signals D and E are put at danger.

With the arrangement of Fig. 1 it wiil be seen that the maximum displacement be tween the currents of the two windings of the track relays is 4.5 degrees, or its equivalent 135 degrees. This means that the track relay torque is not so great as it would be if the currents in the two windings were displaced from each other by 90 degrees. The loss in torque, due to the reduced phase displacement, is proportional to the difference in the sines of 90 and 45 degrees, so that th relays have a torque of approximately of the maximum obtainable with a 90 degree phase displacement. This difference ordinarily is not sufficient to be of any importance, but if, in order to economize in power, it is desired to maintain in the track relays a displacement as near 90 degrees as possible, this result may be obtained by the addition of a second line relay.

One arrangement of employing a second relay is shown in Fig. 6. In this figure I have indicated a three phase generator and transmission system instead of a two phase system, as in Fig. l, and I have shown the transformers arranged with the well-known three-phase, twophase connection, so that two-phase voltages are obtained on the secondary side of these transformers. These two arrangements of transmission systems are in every respect equivalent and either may be used with the arrangement of signal circuits of either Fig. 1 or Fig. 6. The relay C is connected in Fig. 6 as in Fig. 1, while the winding 0 of relay C is connected directly to transformer F, so that conditions in relay C are exactly the same as 1n relay C and the conditions in the windings c of these two relays may be represented by 0 e and 0 i in Fig. 7 for relay C and 0 e and 0 z" in Fig. 9 for relay C. The transformer B is connected to a different phase from that of transformers F and F supplying the windings c of the track relays, so that the voltage supplied to the track by this transformer is displaced 120 degrees, or, 60 degrees from that impressed on the windings 0 of the track relays. The voltage of transformer B may be, consequently, represented by 0 e in Fig. 8, and by properly adjusting the impedance Z), the track current may be made of a phase corresponding to 0 i, which, as shown in Figs. 7 and 9, is approximately degrees out of phase with the currents in the windings c of the relays C and C, so that the relays have the maximum torque. The line cir cuit controlled by relay C and contact d on signal D contains the windings of two line relays G and G. The additional relay G controls the home signal D jointly with the track relay C, so that when relay C is deenergized relay G will be deenergized and signal D will go to stop position. The winding 9 of relay G is connected to transformer F, so that the voltage and current in this winding may be represented in Fig. 11 by 0 o and 0 2' respectively. The winding 9 of relay G is connected across both ransformers F and F, so that the voltage on this winding is 45 degrees displaced from that impressed on the corresponding winding of relay G and may, consequently, be represented in Fig. 10 by 0 e and the current due to this voltage 0 i With the signal D at stop position the line circuit for relays G and G is connected to transformer F so that the voltage and current in this circuit may be represented by 0 e and o i in Fig. 10. The currents 0 i and 0 2' in the two windings of relay G are displaced from each other 4.5 degrees, so that this relay has a torque which closes its contacts so that the circuit of signal D is closed. Comparing the current 0 i in Fig. 10, which is the ourrent in the winding g of both relays G and G, with the current 0 i in Fig. 11, which is the current in the winding 9 of relay G, it will be seen that the two currents are in phase, so that relay G has no torque and its contacts are open. When signal D clears and its contact 03 moves to the other position, the voltage and current in the line circuit are shifted 90 degrees to the positions shown in dotted lines in Figs. 10 and 11 and indicated by 0 e and 0 i". The currents 0 "J and 0 2' in the two windings of relay G are now displaced from each other by 135 degrees, so that the relay has the same torques as before. The currents 0 i and 0 i in the two windings of relay G are now displaced from each other by approximately 90 degrees, so that relay G closes its contacts and closes the circuit of signal E.

In Fig. 6 I have indicated the contact (Z controlled by signal D in the circuit of signal E. This is the usual contact controlled by the home signal in the circuit of the dis tant signal which I omitted in Fig. 1 for the sake of simplicity. To guard against the current from one track circuit affecting the relays of an adjacent track circuit if the insulated joints between them break down, the connections of transformers and relays of adjacent track circuits may be relatively reversed. This reversal is indicated in the drawings, as may be seen by comparing the track connections of relays C and C or of relays O and C in either Fig. l or Fig. 6; it will be noted that similar ends of the track windings of each of these pairs of relays are connected to opposite rails, and that each two adjacent transformers for supplying current to adjacent blocks likewise have their similar ends connected to opposite rails; see B and B. This reversal is more clearly described and claimed in my copending application, Ser. No. 511,663, filed Aug. 7, 1909. It will be apparent with these co11- nections, that at any particular instant, al-

though the currents through the track windings of similar relays are in the same direction, the currents in each two adjacent locks are in opposite directions, and thus the breaking down of the insulation between two blocks will not allow a current through a relay of any block from an adjacent block in a proper direction to give a false clear signal.

It will be obvious to those skilled in the art that many variations of circuits and relays may be employed for embodying my invention, and accordingly I do not desire to limit myself to the particular connections and arrangement of parts shown and described, but aim in the appended claims to cover all modifications.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. In a block signal system, signals for the blocks adapted to indicate danger, caution, and clear, means for supplying alternating current to the track circuit of a block near its middle, a plurality of relays per block including a pair of track relays connected to the two ends of the track circuit respectively, a signal controlling line circuit extending through a block, contacts controlled by the track relay at the exit end oi the block included in said line circuit for opening it when said relay is deenergized, sources of alternating signaling current diiiering in phase for said line circuit, contacts and connections controlled by the signal of the block in advance included in said line circuit for shifting the phase of the current supplied to said circuit when said signal moves from danger to caution, said line circuit including windings oi two of said plurality of relays, one relay responding to current in said line circuit regardless of the shifting of its phase and the other responding to current of one phase only, and contacts controlled by said two relays controlling the caution and clear indications respectively of the signal at the entrance to the block.

2. In a block signal system, track circuits each comprising a source or current, track relays connected to the two ends of each track circuit respectively, a line circuit for each block controlled by the track relay at the exit end of the block, sources of alternating ciu'rent differing in phase for said line circuit, means for each block controlled by the presence and absence of a train in an adjacent block for connecting one or the other of said sources with said line circuit, and a signal for each block controlled by said line circuit and by the track relay at the entrance end of the block.

3. In railway signaling a block, a source of signaling current connected with the rails of the block adjacent the middle point thereof, a track relay connected with the rails adjacent the exit end of the block, a second track relay having two windings one oi which is connected with the rails adjacent the entrance end of the block, a line relay having two windings, means for energizing one winding of the line relay with alternating current, a line circuit for the block controlled by the track relay at Copies of this patent may be obtained for the exit end of the block and including the reniannng wniding of the track relay at the entrance end and the remainlng winding of the line relay, sources of alternating current difiering in phase for said line circuit, means for connecting one or the other of said sources with the line circuit, the track relay at the entrance end being responsive to close its contacts when energized by current of either phase in the line circuit and the line relay being responsive to close its contacts only when energized by current of one phase in the line circuit, and a signal for the block controlled by the line relay and by the track relay at the entrance end oi the block.

4. In railway signaling, a block, a source of signaling current connected with the rails of the block, and two track relays one connected with the rails of the block adjacent each end of the block, a line circuit for the block controlled by the track relay at the exit end of the block, means for supplying to said line circuit alternating currents dili ering in phase, means controlled by the line circuit and responsive in different ways to currents of different phase in the line circuit, and a signal for the block controlled by said last-mentioned means and by the track relay at the entrance end of the block.

5. In railway signaling a block section, a source of signaling current connected with. the rails near the middle oi the block, a plurality of relays for each block including two track relays connected with the rails adjacent the ends of the block respectively, a line circuit for the block controlled by the track relay adjacent the exit end of the block, means for supplying to said line cir- 'cuit alternating currents differing in phase,

said line circuit including windings of two of said relays one relay responding to current of either phase in the line circuit and another relay responding to current of one phase only, and a signal for the block controlled by said last tworelays.

In witness whereof, I have hereunto set my hand this 24ith day of November, 1909.

LAURENCE A. HAWKINS. Witnesses BENJAMIN l3. HULL, HELEN Onronn.

five cents each, by addressing the Commissioner of Eatents,

Washington, D. C. 

